The $dsn is prefixed by 'dbi:InterBase:', and consists of key-value parameters separated by semicolons. New line may be added after the semicolon. The following is the list of valid parameters and their respective meanings:

parameter meaning optional?
-----------------------------------------------------------------
database path to the database required
dbname path to the database
db path to the database
hostname hostname / IP address optional
host hostname / IP address
port port number optional
ib_dialect the SQL dialect to be used optional
ib_role the role of the user optional
ib_charset character set to be used optional
ib_cache number of database cache buffers optional
ib_dbkey_scope change default duration of RDB$DB_KEY optional

database could be used interchangebly with dbname and db. To connect to a remote host, use the host parameter. Here is an example of DSN to connect to a remote Windows host:

Database file alias introduced in Firebird 1.5 can be used too. In the following example, "billing" is defined in aliases.conf:

$dsn = 'dbi:InterBase:hostname=192.168.88.5;db=billing;ib_dialect=3';

Firebird as of version 1.0 listens on port specified within the services file. To connect to port other than the default 3050, add the port number at the end of host name, separated by a slash. Example:

Valid values for ib_dialect are 1, 2, and 3. The driver's default value is 1.

ib_role specifies the role of the connecting user. SQL role is implemented by InterBase to make database administration easier when dealing with lots of users. A detailed reading can be found at:

http://www.ibphoenix.com/ibp_sqlroles.html

If ib_cache is not specified, the default database's cache size value will be used. The InterBase Operation Guide discusses in full length the importance of this parameter to gain the best performance.

available_drivers

@driver_names = DBI->available_drivers;

Implemented by DBI, no driver-specific impact.

data_sources

This method is not yet implemented.

trace

DBI->trace($trace_level, $trace_file)

Implemented by DBI, no driver-specific impact.

DBI Dynamic Attributes

See Common Methods.

METHODS COMMON TO ALL DBI HANDLES

err

$rv = $h->err;

Supported by the driver as proposed by DBI.

errstr

$str = $h->errstr;

Supported by the driver as proposed by DBI.

state

This method is not yet implemented.

trace

$h->trace($trace_level, $trace_filename);

Implemented by DBI, no driver-specific impact.

trace_msg

$h->trace_msg($message_text);

Implemented by DBI, no driver-specific impact.

func

See Transactions section for information about invoking ib_set_tx_param() from func() method.

ATTRIBUTES COMMON TO ALL DBI HANDLES

Warn (boolean, inherited)

Implemented by DBI, no driver-specific impact.

Active (boolean, read-only)

Supported by the driver as proposed by DBI. A database handle is active while it is connected and statement handle is active until it is finished.

Kids (integer, read-only)

Implemented by DBI, no driver-specific impact.

ActiveKids (integer, read-only)

Implemented by DBI, no driver-specific impact.

CachedKids (hash ref)

Implemented by DBI, no driver-specific impact.

CompatMode (boolean, inherited)

Not used by this driver.

InactiveDestroy (boolean)

Implemented by DBI, no driver-specific impact.

PrintError (boolean, inherited)

Implemented by DBI, no driver-specific impact.

RaiseError (boolean, inherited)

Implemented by DBI, no driver-specific impact.

ChopBlanks (boolean, inherited)

Supported by the driver as proposed by DBI.

LongReadLen (integer, inherited)

Supported by the driver as proposed by DBI.The default value is 80 bytes.

Supported by the driver as proposed by DBI. When AutoCommit is On, this method implicitly starts a new transaction, which will be automatically committed after the following execute() or the last fetch(), depending on the statement type. For select statements, commit automatically takes place after the last fetch(), or by explicitly calling finish() method if there are any rows remaining. For non-select statements, execute() will implicitly commits the transaction.

prepare_cached

$sth = $dbh->prepare_cached($statement, \%attr);

Implemented by DBI, no driver-specific impact.

do

$rv = $dbh->do($statement, \%attr, @bind_values);

Supported by the driver as proposed by DBI. This should be used for non-select statements, where the driver doesn't take the conservative prepare - execute steps, thereby speeding up the execution time. But if this method is used with bind values, the speed advantage diminishes as this method calls prepare() for binding the placeholders. Instead of calling this method repeatedly with bind values, it would be better to call prepare() once, and execute() many times.

See the notes for the execute method elsewhere in this document. Unlike the execute method, currently this method doesn't return the number of affected rows.

commit

$rc = $dbh->commit;

Supported by the driver as proposed by DBI. See also the notes about Transactions elsewhere in this document.

rollback

$rc = $dbh->rollback;

Supported by the driver as proposed by DBI. See also the notes about Transactions elsewhere in this document.

disconnect

$rc = $dbh->disconnect;

Supported by the driver as proposed by DBI.

ping

$rc = $dbh->ping;

This driver supports the ping-method, which can be used to check the validity of a database-handle. This is especially required by Apache::DBI.

Database Handle Attributes

AutoCommit (boolean)

Supported by the driver as proposed by DBI. According to the classification of DBI, InterBase is a database, in which a transaction must be explicitly started. Without starting a transaction, every change to the database becomes immediately permanent. The default of AutoCommit is on, which corresponds to the DBI's default. When setting AutoCommit to off, a transaction will be started and every commit or rollback will automatically start a new transaction. For details see the notes about Transactions elsewhere in this document.

Driver (handle)

Implemented by DBI, no driver-specific impact.

Name (string, read-only)

Not yet implemented.

RowCacheSize (integer)

Implemented by DBI, not used by the driver.

ib_softcommit (driver-specific, boolean)

Set this attribute to TRUE to use InterBase's soft commit feature (default to FALSE). Soft commit retains the internal transaction handle when committing a transaction, while the default commit behavior always closes and invalidates the transaction handle.

Since the transaction handle is still open, there is no need to start a new transaction upon every commit, so applications can gain performance improvement. Using soft commit is also desirable when dealing with nested statement handles under AutoCommit on.

Switching the attribute's value from TRUE to FALSE will force hard commit thus closing the current transaction.

STATEMENT HANDLE OBJECTS

Statement Handle Methods

bind_param

Supported by the driver as proposed by DBI. The SQL data type passed as the third argument is ignored.

bind_param_inout

Not supported by this driver.

execute

$rv = $sth->execute(@bind_values);

Supported by the driver as proposed by DBI.

fetchrow_arrayref

$ary_ref = $sth->fetchrow_arrayref;

Supported by the driver as proposed by DBI.

fetchrow_array

@ary = $sth->fetchrow_array;

Supported by the driver as proposed by DBI.

fetchrow_hashref

$hash_ref = $sth->fetchrow_hashref;

Supported by the driver as proposed by DBI.

fetchall_arrayref

$tbl_ary_ref = $sth->fetchall_arrayref;

Implemented by DBI, no driver-specific impact.

finish

$rc = $sth->finish;

Supported by the driver as proposed by DBI.

rows

$rv = $sth->rows;

Supported by the driver as proposed by DBI. It returns the number of fetched rows for select statements, otherwise it returns -1 (unknown number of affected rows).

bind_col

$rc = $sth->bind_col($column_number, \$var_to_bind, \%attr);

Supported by the driver as proposed by DBI.

bind_columns

$rc = $sth->bind_columns(\%attr, @list_of_refs_to_vars_to_bind);

Supported by the driver as proposed by DBI.

dump_results

$rows = $sth->dump_results($maxlen, $lsep, $fsep, $fh);

Implemented by DBI, no driver-specific impact.

Statement Handle Attributes

NUM_OF_FIELDS (integer, read-only)

Implemented by DBI, no driver-specific impact.

NUM_OF_PARAMS (integer, read-only)

Implemented by DBI, no driver-specific impact.

NAME (array-ref, read-only)

Supported by the driver as proposed by DBI.

NAME_lc (array-ref, read-only)

Implemented by DBI, no driver-specific impact.

NAME_uc (array-ref, read-only)

Implemented by DBI, no driver-specific impact.

TYPE (array-ref, read-only)

Supported by the driver as proposed by DBI, with the restriction, that the types are InterBase specific data-types which do not correspond to international standards.

PRECISION (array-ref, read-only)

Supported by the driver as proposed by DBI.

SCALE (array-ref, read-only)

Supported by the driver as proposed by DBI.

NULLABLE (array-ref, read-only)

Supported by the driver as proposed by DBI.

CursorName (string, read-only)

Supported by the driver as proposed by DBI.

Statement (string, read-only)

Supported by the driver as proposed by DBI.

RowCache (integer, read-only)

Not supported by the driver.

TRANSACTION SUPPORT

The transaction behavior is controlled with the attribute AutoCommit. For a complete definition of AutoCommit please refer to the DBI documentation.

According to the DBI specification the default for AutoCommit is TRUE. In this mode, any change to the database becomes valid immediately. Any commit() or rollback() will be rejected.

If AutoCommit is switched-off, immediately a transaction will be started. A rollback() will rollback and close the active transaction, then implicitly start a new transaction. A disconnect will issue a rollback.

InterBase provides fine control over transaction behavior, where users can specify the access mode, the isolation level, the lock resolution, and the table reservation (for a specified table). For this purpose, ib_set_tx_param() database handle method is available.

Upon a successful connect(), these default parameter values will be used for every SQL operation:

Table reservation is supported since DBD::InterBase 0.30. Names of the tables to reserve as well as their reservation params/values are specified inside a hashref, which is then passed as the value of -reserving.

The following example reserves foo_table with read lock and bar_table with read lock and protected access:

Under AutoCommit mode, invoking this method doesn't only change the transaction parameters (as with AutoCommit off), but also commits the current transaction. The new transaction parameters will be used in any newly started transaction.

ib_set_tx_param() can also be invoked with no parameter in which it resets transaction parameters to the default value.

DATE, TIME, and TIMESTAMP FORMATTING SUPPORT

DBD::InterBase supports various formats for query results of DATE, TIME, and TIMESTAMP types.

By default, it uses "%c" for TIMESTAMP, "%x" for DATE, and "%X" for TIME, and pass them to ANSI C's strftime() function to format your query results. These values are respectively stored in ib_timestampformat, ib_dateformat, and ib_timeformat attributes, and may be changed in two ways:

Since locale settings affect the result of strftime(), if your application is designed to be portable across different locales, you may consider using these two special formats: 'TM' and 'ISO'. TM returns a 9-element list, much like Perl's localtime(). The ISO format applies sprintf()'s pattern "%04d-%02d-%02d %02d:%02d:%02d.%04d" for TIMESTAMP, "%04d-%02d-%02d" for DATE, and "%02d:%02d:%02d.%04d" for TIME.

$dbh->{ib_time_all} can be used to specify all of the three formats at once. Example:

$dbh->{ib_time_all} = 'TM';

EVENT ALERT SUPPORT

Event alerter is used to notify client applications whenever something is happened on the database. For this to work, a trigger should be created, which then calls POST_EVENT to post the event notification to the interested client. A client could behave in two ways: wait for the event synchronously, or register a callback which will be invoked asynchronously each time a posted event received.

Associates an event handle with an asynchronous callback. A callback will be passed a hashref as its argument, this hashref contains pair(s) of posted event's name and its corresponding count.

It is safe to call ib_register_callback multiple times for the same event handle. In this case, the previously registered callback will be automatically cancelled.

If the callback returns FALSE, the registered callback will be no longer invoked, but internally it is still there until the event handle goes out of scope (or undef-ed), or you call ib_cancel_callback to actually disassociate it from the event handle.

ib_cancel_callback

$dbh->func($evh, 'ib_cancel_callback');

Unregister a callback from an event handle. This function has a limitation, however, that it can't be called from inside a callback. In many cases, you won't need this function, since when an event handle goes out of scope, its associated callback(s) will be automatically cancelled before it is cleaned up.

UNSUPPORTED SQL STATEMENTS

Here is a list of SQL statements which can't be used. But this shouldn't be a problem, because their functionality are already provided by the DBI methods.

SET TRANSACTION

Use $dbh-func(..., 'set_tx_param')> instead.

DESCRIBE

Provides information about columns that are retrieved by a DSQL statement, or about placeholders in a statement. This functionality is supported by the driver, and transparent for users. Column names are available via $sth->{NAME} attributes.

EXECUTE IMMEDIATE

Calling do() method without bind value(s) will do the same.

CLOSE, OPEN, DECLARE CURSOR

$sth->{CursorName} is automagically available upon executing a "SELECT .. FOR UPDATE" statement. A cursor is closed after the last fetch(), or by calling $sth->finish().

PREPARE, EXECUTE, FETCH

Similar functionalities are obtained by using prepare(), execute(), and fetch() methods.

COMPATIBILITY WITH DBIx::* MODULES

DBD::InterBase is known to work with DBIx::Recordset 0.21, and Apache::DBI 0.87. Yuri Vasiliev <yuri.vasiliev@targuscom.com> reported successful usage with Apache::AuthDBI (part of Apache::DBI 0.87 distribution).

The driver is untested with Apache::Session::DBI. Doesn't work with Tie::DBI. Tie::DBI calls $dbh->prepare("LISTFIELDS $table_name") on which InterBase fails to parse. I think that the call should be made within an eval block.

FAQ

Why do some operations performing positioned update and delete fail when AutoCommit is on?

When AutoCommit is on, a transaction is started within prepare(), and committed automatically after the last fetch(), or within finish(). Within do(), a transaction is started right before the statement is executed, and gets committed right after the statement is executed. The transaction handle is stored within the database handle. The driver is smart enough not to override an active transaction handle with a new one. So, if you notice the snippet above, after the first fetchrow_array(), the do() is still using the same transaction context, but as soon as it has finished executing the statement, it commits the transaction, whereas the next fetchrow_array() still needs the transaction context!

So the secret to make this work is to keep the transaction open. This can be done in two ways:

Using AutoCommit = 0

If yours is default to AutoCommit on, you can put the snippet within a block:

There are cases where placeholders can't be used in conjunction with COLLATE clause, such as this:

SELECT * FROM $table WHERE UPPER(author) LIKE UPPER(? COLLATE FR_CA);

This deals with the InterBase's SQL parser, not with DBD::InterBase. The driver just passes SQL statements through the engine.

How to do automatic increment for a specific field?

Create a generator and a trigger to associate it with the field. The following example creates a generator named PROD_ID_GEN, and a trigger for table ORDERS which uses the generator to perform auto increment on field PRODUCE_ID with increment size of 1.

How can I perform LIMIT clause as I usually do in MySQL?

LIMIT clause let users to fetch only a portion rather than the whole records as the result of a query. This is particularly efficient and useful for paging feature on web pages, where users can navigate back and forth between pages.

Using InterBase (Firebird is explained later), this can be emulated by writing a stored procedure. For example, to display a portion of table_forum, first create the following procedure:

Can I change ib_dialect after DBI->connect ?

Incorrect question. $sth->rows returns the number of fetched rows after a successful SELECT. Starting from version 0.43, execute() method returns the number of affected rows. But it's true that do() method returns -1, this will change in future release.

OBSOLETE FEATURES

Private Method

set_tx_param() is obsoleted by ib_set_tx_param().

TESTED PLATFORMS

Clients

Linux

FreeBSD

SPARC Solaris

Win32

Servers

InterBase 6.0/6.01 SS and Classic for Linux

InterBase 6.0/6.01 for Windows, FreeBSD, SPARC Solaris

FirebirdSS 1.0 Final for Windows, Linux, SPARC Solaris

FirebirdSS 1.5.2.4731 for Windows, Linux

FirebirdSS 2.0 RC4 for Linux. The AMD64 (64-bit) version is also tested. Should also work with Intel EM64T.

BUGS/LIMITATIONS

This module doesn't work with MSWin32 ActivePerl iThreads, and its emulated fork. Tested with MSWin32 ActivePerl build 809 (Perl 5.8.3). The whole process will block in unpredictable manner.

Under Linux, this module has been tested with several different iThreads enabled Perl releases: perl-5.8.0-88 from RedHat 9, perl-5.8.5-9 from Fedora Core 3, perl-5.8.6-15 from Fedora Core 4, and Perl 5.8.[78].

No problem occurred so far.. until you try to share a DBI handle ;-)

But if you plan to use thread, you'd better use the latest stable version of Perl, 5.8.8 has fairly stable iThreads.

Limitations:

Arrays are not (yet) supported

Read/Write BLOB fields block by block not (yet) supported. The maximum size of a BLOB read/write is hardcoded to about 1 MB.

service manager API is not supported.

SEE ALSO

DBI(3).

COPYRIGHT

The DBD::InterBase module is free software. You may distribute under the terms of either the GNU General Public License or the Artistic License, as specified in the Perl README file, with the exception that it cannot be placed on a CD-ROM or similar media for commercial distribution without the prior approval of the author.